The present invention relates to optics in apparatus capable of cartesian scanning and transmitting of large image fields, for instance, larger than 2.degree..times.5.degree..
It is known to use oscillating mirrors, rotating polygons, rotating triple mirrors and also combinations of these components for the purpose of obtaining cartesian raster images in scanning apparatus. The scanning systems provided with these components, however, suffer from a series of imaging defects which substantially degrade the image quality. Thus, oscillating mirrors for instance move the aperture and accordingly prevent optimal adaptation of the detector by FOV (field of view) limitation.
Rotating refracting polygons generate transverse comae at large image angles.
Mirror polygons suffer from the same drawback as the oscillating mirrors, namely they move the aperture and therefore require a very large detector aperture.
Rotating triple reflectors do not generate a linear raster.